The Messenger of Allah (ṣ) saw a person prostrating on part of his turban, so he gestured to him to remove (that part of) the turban, pointing to his forehead.”[1

“The Messenger of Allah (ṣ) saw a person prostrating on part of his turban, so he gestured to him to remove (that part of) the turban, pointing to his forehead.”[1]

From these traditions it becomes clear that in the time of the Holy Prophet (ṣ) the need to prostrate on earth was beyond dispute and it was such that if one of the Muslims put part of his turban between his forehead and the ground, he would be prohibited by the Prophet (ṣ) from doing so.

6. The infallible Imāms followed by the Shī‘ah who, according to the Hadīth ath-Thaqalayn, are the inseparable peer of the Qur’an, as well as members of the Prophet’s Household [Ahl al-Bayt], emphasize this fact in their speeches:

Imām aṣ-Ṣādiq (‘a) says:

“.سنّة الخمرة علىٰ و فريضة الأرض علىٰ السجود”

“Prostration on the earth is obligatory while prostrating on a straw mat is a sunnah.”[2]

He (‘a) also says:

“.لبس أو أكل ما إلا الأرض أنبتت ما علىٰ أو الأرض علىٰ إلاّ لايجوز السجود”

“It is not permissible to prostrate on anything except the earth or what grows in it excluding that which is eaten or worn.”[3]

Conclusion

From the aggregate of the stated proofs, it becomes very clear that not only the traditions of the Ahl al-Bayt (‘a) but also the Sunnah of the Messenger of Allah (ṣ) and the actions of his Companions and Followers [Tābi‘ūn] testify to the necessity of prostrating on the earth and what grows in it (excluding that which is worn and eaten).

In addition, the permissibility of prostration on the mentioned things is definite whereas the permissibility of prostration on other things is doubtful and disputable. Therefore, by precaution—which is the way to attain deliverance and uprightness—it is appropriate to prostrate on the mentioned things only.

Finally, it should be noted that this discussion is a fiqhī question and differences among Muslim jurists concerning such minor issues are very common, but such differences should not be a source of concern because these differences are also common among the four Sunnī fiqhī schools. For example, the Mālikīs say that placing the nose on the place of prostration is recommended [mustaḥabb] while the Ḥanbalīs consider it obligatory [wājib] and say that ignoring it renders the prayer invalid [bāṭil].[4]